RFID's ability to precisely identify objects at low cost and without line of sight is enabling new applications in supply-chain management, retail sales, anticounterfeiting, healthcare, and other fields. However, researchers must overcome some major hurdles before these benefits can be realized. One is managing RFID data, which is noisy, generated dynamically in very large streams, has a limited active lifespan, and possesses useful contextual characteristics such as temporality, spatiality, and implicit semantics. Deployment of large-scale RFID applications also introduces unique scalability and heterogeneity challenges. Security and privacy concerns also inhibit adoption of the technology.

XML Document Parsing: Operational and Performance Characteristics

pp. 30–37

Tak Cheung Lam, Jianxun Jason Ding, and Jyh-Charn Liu

XML-based database and networking applications have unique requirements with respect to access and modification of parsed data. Database applications must be able to access and modify the document structure back and forth, while networking applications rely on one-pass access and modification during parsing. To help developers make sensible choices for their target applications, the authors compared the data representations of four representative parsing models: document object model (DOM), simple API for XML (SAX), streaming API for XML (StAX), and virtual token descriptor (VTD).

Massively multiplayer online games have become a popular multiuser-based networked application. These MMOGs provide a structured virtual environment where players can interact cooperatively or competitively with other players, thus promoting the creation of social bonds.

In contrast, massively multiplayer online worlds provide a distinctly separate multiuser-based genre. These MMOWs differ by providing an unstructured virtual environment that includes mechanisms for players to introduce new original objects and avatar behaviors. This added overhead, however, requires reducing network bandwidth demands on the servers and user clients when the system distributes or updates user-created content.

Unlike traditional online games, metaverses must dynamically provide content—which is mostly user-generated and continually modified—to users depending on their location in the virtual world. To better understand this emerging type of application, the authors performed a detailed analysis of Second Life, a popular metaverse, and determined that its computational and communication requirements place significant demands on servers, clients, and the network. As virtual worlds evolve to support more users, interaction types, and realism, these demands will increase.

Everybody Share: The Challenge of Data-Sharing Systems

pp. 54–61

Ken Smith, Len Seligman, and Vipin Swarup

Individuals, businesses, and government agencies increasingly share vast quantities of data via a wide range of technologies, including Web services, data warehouses, portals, RSS feeds, and P2P file sharing. Researchers have typically addressed the challenges of data sharing from the perspective of a single technology, such as Web services, or have emphasized one aspect, such as semantic integration or digital rights management.

However, enterprise architects and technology planners require a general framework that applies across a broad range of implementation technologies. The authors present such a framework and illustrate its conceptual features with several examples.

Although academic interest in computational grids may have peaked, it spawned awareness of a new operational mode for computational data centers, utility computing. In this mode, the system assigns compute resources to customers on demand.

A utility computing data center dynamically creates virtual servers containing a subset of the available resources to fulfill user demands. The jobs or services running in a UCDC typically have diverse characteristics, such as different resource requirements, running times, software quality, security requirements, and importance.